不同裂缝损伤和愈合温度条件下沥青自愈合行为的分子模拟

Molecular simulation of self-healing behavior of asphalt under different crack damage and healing temperature

为研究在不同裂缝损伤和愈合温度条件下沥青的自愈合行为,通过分子动力学(MD)方法构建沥青分子模型,模拟70#基质沥青在温度313~333K、裂缝宽度10~50Å(1Å=0.1nm)条件下的自愈合行为,从沥青分子模型的密度、径向分布函数、玻璃化转变温度、内聚能密度以及溶解度参数验证了沥青分子模型的合理性;从定性(密度、均方位移)和定量(扩散系数、内聚能密度和自由体积分数)两个方面评价了沥青分子模型的自愈合性能。结果表明,自愈合温度为313~333K时,不同裂缝宽度的愈合模型内聚能密度波动范围在0.2%~3%,表明沥青分子的自愈合对该温度区间的温度变化不敏感;沥青分子模型裂缝宽度为30?时,模型的愈合过程明显,且愈合效果也最好,推荐采用30?作为70#基质沥青愈合模型的裂缝宽度。

In order to study the self-healing behavior of asphalt under different crack damage and healing temperatures,a molecular model of asphalt was constructed by molecular dynamics(MD)method to simulate the self-healing behavior of 70#matrix asphalt under the conditions of temperature 313—333K and crack width 10—50Å.The rationality of the asphalt molecular model was verified from the density of asphalt molecular model,radial distribution function,glass transition temperature,cohesive energy density and solubility parameters.The self-healing ability of asphalt molecular model was evaluated qualitatively(density and mean square displacement)and quantitatively(diffusion coefficient,cohesive energy density and free volume fraction).The results showed that when the self-healing temperature was 313—333K,the cohesive energy density of the healing models with different crack widths fluctuated in the range of 0.2%—3%,indicating that the self-healing of asphalt molecules was insensitive to the temperature change in this temperature range.When the crack width of asphalt molecular model was 30Å,the healing process of the model was obvious and the healing effect was also the best.It was recommended to use 30Åas the crack width of 70#matrix asphalt healing model.